This invention relates to a vehicle runnning control system having composite function of preventing slip on drive wheels at starting and acceleration of the vehicle and controlling a running speed of the vehicle during running.
A conventional system of the type for preventing slip on the drive wheels has been disclosed in Japanese Publication No. 51-31915 entitled "Device for preventing Slip on Drive Wheel", wherein an opening degree of a carburetor (throttle) of an engine is decreased to reduce engine torque upon occurrence of the slip on the drive wheels.
The conventional system is provided with an actuator for slip prevention purpose only. However, in the case that a running speed control system (automatic drive) for controlling a vehicle running speed during running is provided in the vehicle, an actuator for opening and closing the throttle as required for the automatic drive must regulate the throttle opening degree accurately to an arbitral angle. Therefore, the automatic drive actuator has a performance remarkably different from that of the slip preventing actuator as above-mentioned which is designed to temporarily close the throttle with high speed responsibility, and the automatic drive actuator may not be simply combined with the preventing actuator. Accordingly, it is disadvantageously necessary to provide discrete actuators for the automatic drive and the slip prevention.
Further, in the conventional system as above-mentioned, a throttle shaft is directly connected through an accelerator cable to an accelerator pedal. Therefore, when the throttle opening degree is forcibly decreased by operating the slip preventing actuator, a repulsive force against a driving force of the actuator acts to push back the accelerator pedal and apply shock to a driver's foot.
As is mentioned above, the conventional system is not practical in the above various points.